Self-healing pavements using microcapsules containing rejuvenator: from idea to real application sciencedirect.com

Abstract
Microencapsulated rejuvenator powder was first reported by Jun-Feng Su and Erik Schlangen in 2011. These smart microcapsules are designed to repair microcracks and improve self-healing ability of aged bitumen. Currently, the self-healing microcapsule product has attracted much attention and it is believed to be a promising approach to prolong the service life of pavements. These microcapsules need to remain their integrity in bitumen matrix with necessary special characteristics such as excellent mechanical properties, thermal stability, and compactability. This chapter first introduced the fabrication method of microcapsules containing oily rejuvenator, including controlling the mean size, shell thickness, mechanical property, and thermal stability. Second, the states of microcapsules in pure bitumen and asphalt were observed systemically. Microcapsules were dispersed in bitumen with a homogeneous state without break. No interface debonding phenomenon appeared between the microcapsules and bitumen. Microscopic observation results revealed that microcapsules could be pierced by microcracks in the asphalt binder and the encapsulated rejuvenator flowed out under the force of capillary action. Microcrack triggered the break of microcapsules. The rejuvenator flowed out smoothly and rejuvenated the aged bitumen with the help of capillary, diffusion, and penetration. Properties of virgin and rejuvenated bitumen also confirmed that the aged bitumen had a multirecovery ability due to the microcapsules containing rejuvenator. Third, two types of mechanical methods were used to evaluate the self-healing capability of microcapsules/bitumen samples. Based on the above research, this chapter also introduced the world’s first self-healing pavement in China. The self-healing result of a real application proved that the product of microcapsules containing rejuvenator is a promising approach to prolong the service life of pavements.